It would be advantageous to create a vehicular structural member such as a motor compartment rail, suspension control arm or suspension subframe beam from a closed section hollow element that utilizes a conventional clamshell configuration but eliminates the overlapped joint of the prior art. It has been proven that for large volume applications such as those dictated by the automotive industry. Sheet metal press forming is the most cost-effective method of manufacturing structural components. Almost every vehicle currently produced utilizes a body structure and selected subframes constructed almost entirely from either aluminum or steel stampings manufactured using press forming techniques. Wherever closed section hollow elements are required they are generally constructed from two press formed open section sheet metal components, creating a clamshell configuration using either an overlapping section to facilitate a suitable fillet type weld joint or an outstanding flange to provide a double material spot weld joint. The primary aim of the present disclosure is to eliminate the redundant material associated with overlapping or flange type joints in clamshell closed section hollow elements.
The most efficient type of weld joint is a butt arrangement where the two components being structurally joined meet along a tangent interface at their open edges so that there is no overlapping of material. This butt joint can then be welded using MIG, TIG, Arc, Laser or similar means creating a continuous structural attachment of the two components. The quality of this welded butt joint is extremely sensitive to the gap between the two components and the differential thickness of the materials of the two components. The differential thickness can be controlled by correct specification during the design process. The gap between the two components is dependent on manufacturing process capability. When the two components are constructed from stamped sheet metal using press formed techniques the open edges cannot be developed to interface with a zero gap due to limitations in the process. It is for this reason that press formed clamshell configurations use either an overlapping section to facilitate a suitable fillet type weld joint or an outstanding flange to provide a double material spot weld joint.